The Yahoo logo is displayed in front of the Yahoo headqarters on July 17, 2012 in Sunnyvale, California. / Justin Sullivan, Getty Images

by Carol Kopp, Minyanville

by Carol Kopp, Minyanville

The folks at Yahoo must have danced with joy when their new logo design was widely ridiculed and panned.

They had changed their logo. And somebody noticed.

Anybody who has ever worked at a Web company on the skids knows that stopping that downward momentum is a near impossibility. And yet, it looks like Marissa Mayer, in the CEO's job only since July 2012, might have pulled it off. People are paying attention to Yahoo again.

A lot of those people are investors. The stock's price has doubled during her time in the role, to $30.64 as of Monday's close. That adds about $14 billion to shareholder value.

Over the past year, the company has gone on a massive shopping spree, buying up 19 mobile app and social media companies. The most notable of these purchases was the micro-blogging platform Tumblr, and many of the others were talent purchases more than content acquisitions.

But virtually all of the other changes are superficial, and that is not meant to be disparaging. Yahoo had that tired, out-of-date and abandoned look that a dying business gets in its last days, and Mayer has shaken it out of its stupor.

Yahoo's appearance is critical, especially as Mayer appears to be moving the site more firmly toward the content-publishing model, and away from its original identity as a search engine.

Among the changes made in the past year:

My.Yahoo.com, the long-moribund personalized home page, has been revived, with a focus on relevant, local, and timely information, and slots for updates from Facebook and LinkedIn. The modular design looks like it was made for mobile, and not accidentally. The display advertising is eye-catching and looks professionally-produced, which is more than either Facebook or Google has ever managed to pull off.

The local weather page has been revamped, with dramatic, changing background images and detailed local information.

Email has gotten a new clean and minimalist look.

The sports section has gotten a distinctive look of its own.

And that is pretty much the big four of editorial content, at least in terms of capturing repeated daily page hits from consumers who advertisers want to reach.

Where is all this going? It looks like Mayer is trying to reestablish Yahoo in its old role as a home page for the Internet. But the Internet has come a long way since then, so this new home page has to be different for every user, and far more dynamic than was possible back in the "old days" of Yahoo.

Since Yahoo and its then-biggest competitor, AOL, started their long slide into oblivion five years ago or more, the Web has had no "front page." Users go to Google to search, to Facebook to schmooze, to one or more general or specialized sites to read the news, and to an email provider for correspondence.

Serendipity is great, but it would be nice if somebody figured out a way to pull it all together in one page. That is what Mayer seems to be trying to do.

She claims that Yahoo has increased monthly traffic by 20%, to more than 800 million monthly users, excluding Tumblr.

It is especially significant that 350 million of those users were on mobile devices.

Yahoo, at least briefly, regained the top slot in comScore's Web traffic rankings in the July numbers, passing Google for the first time in two years. But some analysts discounted the importance of that report, in part because it did not include mobile usage.

So, a key question when Yahoo reports its quarterly earnings on Oct. 21 will be whether that increasing mobile usage is translating into ad dollars. Its display ad revenue overall was down 11% in the last quarter, not a good trend.

Mayer does not underplay the challenges ahead. At a recent conference, she said it would take "three or more" years for Yahoo to get where it needs to be.